feat: integrate Tailwind CSS and implement dark mode functionality

- Added Tailwind CSS dependencies and configured PostCSS.
- Updated app component to wrap router outlet with a styled div for dark mode support.
- Modified routing to include a default route and added auth guards.
- Implemented dark mode toggle functionality in content component.
- Enhanced login component with improved styling and lifecycle management.
- Created items component with basic structure and routing.
- Added global styles for body and dark mode variants.
- Updated tests for new items component.

Web/package.json

@@ -20,12 +20,14 @@
   },
   "private": true,
   "dependencies": {
+    "@angular/cdk": "^20.1.4",
     "@angular/common": "^20.0.0",
     "@angular/compiler": "^20.0.0",
     "@angular/core": "^20.0.0",
     "@angular/forms": "^20.0.0",
     "@angular/platform-browser": "^20.0.0",
     "@angular/router": "^20.0.0",
+    "@tailwindcss/postcss": "^4.1.11",
     "angular-oauth2-oidc": "^20.0.2",
     "rxjs": "~7.8.0",
     "tslib": "^2.3.0"
@@ -34,13 +36,17 @@
     "@angular/build": "^20.0.6",
     "@angular/cli": "^20.0.6",
     "@angular/compiler-cli": "^20.0.0",
+    "@tailwindcss/cli": "^4.1.11",
     "@types/jasmine": "~5.1.0",
+    "autoprefixer": "^10.4.21",
     "jasmine-core": "~5.7.0",
     "karma": "~6.4.0",
     "karma-chrome-launcher": "~3.2.0",
     "karma-coverage": "~2.2.0",
     "karma-jasmine": "~5.1.0",
     "karma-jasmine-html-reporter": "~2.1.0",
+    "postcss": "^8.5.6",
+    "tailwindcss": "^4.1.11",
     "typescript": "~5.8.2"
   }
 }